Digital video encoding such as MPEG (Moving Pictures Expert Group) compliant digital video has become a popular encoding mechanism that permits digital storage, transmission and reproduction of video images such as television programs and movies. The transition from analog to digital has made PVR's (personal video recorders), also known as DVR's (digital video recorders), an increasingly popular technology. PVR's are used to store digital video content using digital technologies such as hard disc drives.
Users of such PVR devices have come to expect such devices to be capable of so-called “trick play” operation that resembles operation of video tape recorders (VTR's). Trick play operation includes, but is not limited to, fast forward, reverse, fast reverse, jump and skip functions. Most digital coding techniques such as MPEG compliant encoding utilize significant levels of compression. Such compression is implemented by use of predictive coding techniques in which certain frames of video are dependent upon and utilize information in other frames of video. For example, MPEG I frames (intra-coded frames) stand alone, while B frames and P frames (Inter-coded frames) are dependent upon and use information presented in other frames.
Such encoding techniques were designed for normal speed forward play of video. Predictive coding techniques complicate trick mode play. Most commonly, when trick play, such as reverse mode trick play, is implemented, the result is a jerky or freeze frame-like image that is sometimes implemented by only playing back I frames (which do not depend on other frames). Sometimes the I frames are repeated to fill in for missing video frames. As a result, trick play is often only a crude approximation of that which can be obtained with analog VTR technology.